The field of the invention relates to bio-telemetry in general and specifically to bio-telemetry systems capable of providing patient location information.
Bio-telemetry systems are now widely used to monitor patients in cardiac care and rehabilitation centers. Most existing telemetry monitors are capable of monitoring only cardiac rhythm and do not possess the requisite bandwidth and other features essential for an accurate analysis of a wide variety of cardiac arrhythmias. Development of a biotelemetry system suitable for providing a diagnostic quality multilead electrocardiogram (ECG) signal is highly desirable. Such a system would then permit use of modern real time analyses arrhythmia monitors on ambulatory patients.
Prior bio-telemetry systems are mostly single ECG channel systems. For example, the one disclosed in U.S. Pat. No. 3,953,848. A number of multi-lead ECG telemetry systems have also been described. Examples are those disclosed in U.S. Pat. Nos. 3,962,697; 3,815,109 and 4,356,486. These attempts are useful contributions to the field but the radio frequency bandwidth required by these systems does not permit monitoring of a large number of patients in the same hospital.
In an event of a detected serious arrhythmic episode, a patient must be located quickly so that life saving measures can be initiated. Thus, it is also desirable to have an automatic patient location capability in the monitoring system.
U.S. Pat. No. 4,593,273 discloses an out-of-range personnel monitor and alarm. Although this system may sound an alarm if a patient walks out of range, it does not help hospital personnel in locating the patient. It also implicitly limits the freedom of the patient to move about.
Further, the existing systems do not readily adapt to the transmission of other useful information, such as patient temperature, patient distress, pacer spikes, blood oxygen, electrodes and the status of the equipment itself.